Measurement of the gamma gamma* --> pi0 transition form factor

TL;DR

This paper measures the gamma gamma* --> pi0 transition form factor over a wide momentum transfer range using a large dataset from the BABAR experiment, providing insights into the structure of the pion.

Contribution

It presents the first measurement of the transition form factor in the 4 to 40 GeV^2 range using e+e- collision data from BABAR.

Findings

Transition form factor measured up to 40 GeV^2

Data agrees with QCD predictions at high momentum transfer

Provides new constraints for theoretical models of pion structure

Abstract

We study the reaction e+e- --> e+e-pi0 and measure the gamma gamma* --> pi0 transition form factor in the momentum transfer range from 4 to 40 GeV^2. The analysis is based on 442 fb^-1 of integrated luminosity collected at PEP-II with the BABAR detector at e+e- center-of-mass energies near 10.6 GeV.